joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.4, joserfc.jws.deserialize_json() accepts a JWS General JSON Serialization with an empty signatures array as authenticated. The verify_general_json() loop performs no iterations for the empty array and returns success because no signature check failed, allowing an attacker without a signing key to supply an arbitrary payload that relying applications may treat as authentic.
The issue affects the General JSON Serialization path; compact JWS and JWT decoding, Flattened JSON serialization, and JWE JSON processing do not follow this vulnerable path. This issue is fixed in version 1.7.4.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/authlib/joserfc/commit/f409f8f058225d7686acab6546c94593e4c1b…
security-advisories@github.com
https://github.com/authlib/joserfc/releases/tag/1.7.4
security-advisories@github.com
https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2
security-advisories@github.com